Fix a framework failure on Windows when accepting output, and allow

accepting output when the output file does not exist (it is now
created).

testsuite/driver/testlib.py

@@ -1398,9 +1398,10 @@ def compare_outputs( kind, normaliser, extra_normaliser,
     if os.path.exists(expected_file):
         expected_raw = read_no_crs(expected_file)
         expected_str = extra_normaliser(normaliser(expected_raw))
+        expected_file_for_diff = expected_file
     else:
         expected_str = ''
-        expected_file = '/dev/null'
+        expected_file_for_diff = '/dev/null'
 
     actual_raw = read_no_crs(actual_file)
     actual_str = extra_normaliser(normaliser(actual_raw))
@@ -1408,12 +1409,12 @@ def compare_outputs( kind, normaliser, extra_normaliser,
     if expected_str != actual_str:
         print 'Actual ' + kind + ' output differs from expected:'
 
-        if expected_file == '/dev/null':
+        if expected_file_for_diff == '/dev/null':
             expected_normalised_file = '/dev/null'
-
         else:
             expected_normalised_file = expected_file + ".normalised"
             write_file(expected_normalised_file, expected_str)
+
         actual_normalised_file = actual_file + ".normalised"
         write_file(actual_normalised_file, actual_str)
 
@@ -1425,24 +1426,18 @@ def compare_outputs( kind, normaliser, extra_normaliser,
         # (including newlines) so the diff would be hard to read.
         # This does mean that the diff might contain changes that
         # would be normalised away.
-        r = os.system( 'diff -uw ' + expected_file + \
+        r = os.system( 'diff -uw ' + expected_file_for_diff + \
                                ' ' + actual_file )
 
         # If for some reason there were no non-whitespace differences,
         # then do a full diff
         if r == 0:
-            r = os.system( 'diff -u ' + expected_file + \
+            r = os.system( 'diff -u ' + expected_file_for_diff + \
                                   ' ' + actual_file )
 
         if config.accept:
-            if expected_file == '':
-                print '*** cannot accept new output: ' + kind + \
-                      ' file does not exist.'
-                return 0
-            else:
-                print 'Accepting new output.'
-                write_file(expected_file, actual_raw)
-                return 1
+            print 'Accepting new output.'
+            write_file(expected_file, actual_raw)
         return 0
     return 1